Project summary Aging is the process of decline over time that affects all organisms. Understanding the mechanisms behind the aging process in model systems could ultimately lead to the prevention of age-related decline and disease in humans. C. elegans is an excellent model system to study aging and many genes and interventions have been identified that delay aging. For instance, reduction of insulin/IGF1 or removal of the germline stem cells robustly increases hermaphrodite lifespan. Sex specific differences in longevity are seen throughout the animal kingdom, including in humans. Even though C. elegans is an established aging model system, male lifespan has been largely neglected, since classic single sex group aging experiments used for hermaphrodites dramatically shorten male lifespan. Single males leave the agar dishes in search of mates making classic aging experiments with males technically difficult. Using a liquid 96-well aging assay, we propose to test how males respond to mutations and interventions that are known to extend hermaphrodite lifespan to identify sex-specific differences in lifespan regulation in C. elegans and characterize how and where these differences occur. So far, we found at least one intervention, ablation of the germline, elicits a sex specific response: in contrast to hermaphrodites, male lifespan does not change significantly upon germline loss. Indeed, sex specific differences are reported for many of the important downstream regulators of hermaphrodite lifespan regulation. For instance, hormone and insulin signaling, as well as ascarosides, small molecules produced by the worms, show sex-specific profiles. However, these signals have not been studied in regard to the effect on lifespan. In this proposal, we aim to first catalog the male lifespan in response to known hermaphrodite lifespan changing interventions such as mutations in insulin signaling, TOR signaling, AMPK signaling, and mitochondrial respiratory chain components and interventions such as dietary restriction and addition of specific ascarosides. In our second aim, we will investigate the molecular mechanisms behind the observed sex-specific differences. For example, for germline ablation, we will investigate the metabolic changes that occur (or fail to occur) upon germ cell stem cell loss in hermaphrodites and males using NMR spectroscopy and HPLC-MS to identify the signal from the germline stem cells that regulates longevity. Finally, in Aim 3, we will determine the nature and tissue localization of the sex-specific differences in lifespan using strains with sex reversal in specific tissues. Such research will help us understand specific processes affect the lifespan of organisms in a sex specific manner. 1